An electric vehicle, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or the like, generally includes an electric motor, which may alone propel the vehicle in an electric vehicle (EV), or charge depleting, drive mode. The vehicle may also include an internal combustion engine (ICE) to serve as the primary, or range extending, propulsion system of the vehicle, or to operate in conjunction with the electric motor in a hybrid, or charge sustaining, mode.
The electric motor generally receives electric power from an electric power source, such as a rechargeable energy storage system (RESS). The RESS may include a battery pack or other rechargeable energy storage means capable of storing large amounts of energy. The energy stored in the RESS dissipates, and as such, the RESS needs to be recharged. This may be done when the vehicle is in an active drive state through regenerative braking, where the vehicle employs such a system. Alternatively, the charging may be accomplished when the vehicle is in an inactive charging state, in which the vehicle may be plugged into an electrical source, such as the electrical grid. In colder ambient temperatures, the charge depletes faster, due to various factors. As such, the distance the vehicle may travel in EV drive mode, or the EV range, is reduced in the colder ambient temperatures.
The RESS requires a thermal system for cooling and warming the battery pack to maximize the charging capacity and life of the battery pack. The thermal system generally includes a coolant line that runs through the RESS. Currently, the RESS may be heated using a high voltage heater on the coolant line. The RESS may be cooled with ambient air by running the coolant line through an ambient-to-liquid radiator. The RESS may also be cooled by exchanging heat in the coolant line with an air-conditioning (A/C) refrigeration loop by way of a chiller in parallel with a cabin evaporator.